content: /* ===========================================================
   * JFreeChart : a free chart library for the Java(tm) platform
   * ===========================================================
   *
   * (C) Copyright 2000-2012, by Object Refinery Limited and Contributors.
   *
   * Project Info:  http://www.jfree.org/jfreechart/index.html
   *
   * This library is free software; you can redistribute it and/or modify it
   * under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation; either version 2.1 of the License, or
   * (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
   * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
   * License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
   * USA.
   *
   * [Oracle and Java are registered trademarks of Oracle and/or its affiliates.
   * Other names may be trademarks of their respective owners.]
   *
   * --------------
   * LogFormat.java
   * --------------
   * (C) Copyright 2007-2009, by Object Refinery Limited and Contributors.
   *
   * Original Author:  David Gilbert (for Object Refinery Limited);
   * Contributor(s):   -;
   *
   * Changes
   * -------
   * 02-Aug-2007 : Version 1 (DG);
   * 19-Feb-2008 : Implemented equals() and clone(), and added new powerLabel
   *               attribute as per Feature Request 1886036 (DG);
   * 14-Jan-2009 : Added default constructor, and accessor methods for
   *               exponent formatter (DG);
   *
   */
  
  package org.jfree.chart.util;
  
  import java.text.DecimalFormat;
  import java.text.FieldPosition;
  import java.text.NumberFormat;
  import java.text.ParsePosition;
  
  /**
   * A number formatter for logarithmic values.  This formatter does not support
   * parsing.
   *
   * @since 1.0.7
   */
  public class LogFormat extends NumberFormat {
  
      /** The log base value. */
      private double base;
  
      /** The natural logarithm of the base value. */
      private double baseLog;
  
      /** The label for the log base (for example, "e"). */
      private String baseLabel;
  
      /**
       * The label for the power symbol.
       *
       * @since 1.0.10
       */
      private String powerLabel;
  
      /** A flag that controls whether or not the base is shown. */
      private boolean showBase;
  
      /** The number formatter for the exponent. */
      private NumberFormat formatter = new DecimalFormat("0.0#");
  
      /**
       * Creates a new instance using base 10.
       *
       * @since 1.0.13
       */
      public LogFormat() {
          this(10.0, "10", true);
      }
  
      /**
       * Creates a new instance.
       *
       * @param base  the base.
       * @param baseLabel  the base label (<code>null</code> not permitted).
       * @param showBase  a flag that controls whether or not the base value is
       *                  shown.
       */
      public LogFormat(double base, String baseLabel, boolean showBase) {
          this(base, baseLabel, "^", showBase);
      }
  
      /**
       * Creates a new instance.
       *
       * @param base  the base.
       * @param baseLabel  the base label (<code>null</code> not permitted).
       * @param powerLabel  the power label (<code>null</code> not permitted).
       * @param showBase  a flag that controls whether or not the base value is
       *                  shown.
       *
       * @since 1.0.10
       */
      public LogFormat(double base, String baseLabel, String powerLabel,
              boolean showBase) {
          if (baseLabel == null) {
              throw new IllegalArgumentException("Null 'baseLabel' argument.");
          }
          if (powerLabel == null) {
              throw new IllegalArgumentException("Null 'powerLabel' argument.");
          }
          this.base = base;
          this.baseLog = Math.log(this.base);
          this.baseLabel = baseLabel;
          this.showBase = showBase;
          this.powerLabel = powerLabel;
      }
  
      /**
       * Returns the number format used for the exponent.
       *
       * @return The number format (never <code>null</code>).
       *
       * @since 1.0.13.
       */
      public NumberFormat getExponentFormat() {
          return (NumberFormat) this.formatter.clone();
      }
  
      /**
       * Sets the number format used for the exponent.
       *
       * @param format  the formatter (<code>null</code> not permitted).
       *
       * @since 1.0.13
       */
      public void setExponentFormat(NumberFormat format) {
          if (format == null) {
              throw new IllegalArgumentException("Null 'format' argument.");
          }
          this.formatter = format;
      }
  
      /**
       * Calculates the log of a given value.
       *
       * @param value  the value.
       *
       * @return The log of the value.
       */
      private double calculateLog(double value) {
          return Math.log(value) / this.baseLog;
      }
  
      /**
       * Returns a formatted representation of the specified number.
       *
       * @param number  the number.
       * @param toAppendTo  the string buffer to append to.
       * @param pos  the position.
       *
       * @return A string buffer containing the formatted value.
       */
      @Override
      public StringBuffer format(double number, StringBuffer toAppendTo,
              FieldPosition pos) {
          StringBuffer result = new StringBuffer();
          if (this.showBase) {
              result.append(this.baseLabel);
              result.append(this.powerLabel);
          }
          result.append(this.formatter.format(calculateLog(number)));
          return result;
      }
  
      /**
       * Formats the specified number as a hexadecimal string.  The decimal
       * fraction is ignored.
       *
       * @param number  the number to format.
       * @param toAppendTo  the buffer to append to (ignored here).
       * @param pos  the field position (ignored here).
       *
       * @return The string buffer.
       */
      @Override
      public StringBuffer format(long number, StringBuffer toAppendTo,
              FieldPosition pos) {
          StringBuffer result = new StringBuffer();
          if (this.showBase) {
              result.append(this.baseLabel);
              result.append(this.powerLabel);
          }
          result.append(this.formatter.format(calculateLog(number)));
          return result;
      }
  
      /**
       * Parsing is not implemented, so this method always returns
       * <code>null</code>.
       *
       * @param source  ignored.
       * @param parsePosition  ignored.
       *
       * @return Always <code>null</code>.
       */
      @Override
      public Number parse (String source, ParsePosition parsePosition) {
          return null; // don't bother with parsing
      }
  
      /**
       * Tests this formatter for equality with an arbitrary object.
       *
       * @param obj  the object (<code>null</code> permitted).
       *
       * @return A boolean.
       */
      @Override
      public boolean equals(Object obj) {
          if (obj == this) {
              return true;
          }
          if (!(obj instanceof LogFormat)) {
              return false;
          }
          LogFormat that = (LogFormat) obj;
          if (this.base != that.base) {
              return false;
          }
          if (!this.baseLabel.equals(that.baseLabel)) {
              return false;
          }
          if (this.baseLog != that.baseLog) {
              return false;
          }
          if (this.showBase != that.showBase) {
              return false;
          }
          if (!this.formatter.equals(that.formatter)) {
              return false;
          }
          return super.equals(obj);
      }
  
      /**
       * Returns a clone of this instance.
       *
       * @return A clone.
       */
      @Override
      public Object clone() {
          LogFormat clone = (LogFormat) super.clone();
          clone.formatter = (NumberFormat) this.formatter.clone();
          return clone;
      }
  
  }
  